We report a new ternary Zn 2 SnO 4 (ZSO) electron-transporting electrode of a CH 3 NH 3 PbI 3 perovskite solar cell as an alternative to the conventional TiO 2 electrode. The ZSO-based perovskite solar cells have been prepared following a conventional procedure known as a sequential (or two-step) process with ZSO compact/mesoscopic layers instead of the conventional TiO 2 counterparts, and their solar cell properties have been investigated as a function of the thickness of either the ZSO compact layer or the ZSO mesoscopic layer. The presence of the ZSO compact layer has a negligible influence on the transmittance of the incident light regardless of its thickness, whereas the thickest compact layer blocks the back-electron transfer most efficiently. The open-circuit voltage and fill factor increase with the increasing thickness of the mesoscopic ZSO layer, whereas the short-circuit current density decreases with the increasing thickness except for the thinnest one (∼100 nm). As a result, the device with a 300 nmthick mesoscopic ZSO layer shows the highest conversion efficiency of 7%. In addition, time-resolved and frequency-resolved measurements reveal that the ZSO-based perovskite solar cell exhibits faster electron transport (∼10 times) and superior charge-collection capability compared to the TiO 2 -based counterpart with similar thickness and conversion efficiency.

The mechanism behind superconformal filling of fine features during surfactant catalyzed chemical vapor deposition ͑CVD͒ is described and the metrology required to predict it is identified and quantified. The impact of adsorbed iodine coverage on copper deposition rate during chemical vapor deposition of copper on planar substrates is determined first. These kinetic parameters are then used in a model based on the curvature-enhanced accelerator coverage mechanism to predict superconformal filling during iodine-catalyzed CVD. In this model, the coverage of the adsorbed catalyst is presumed to change with surface area during interface evolution. The surface area decreases along the bottoms of submicrometer dimension features, increasing the local coverage and deposition rates and thereby enabling superconformal filling. Experimental filling results are then described and shown to be consistent with the predictions.

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